Studies of Selected Spermatophytes. 247 



position which nature has given it. That was beginning 

 at the right end of the question, for as soon as I lifted the 

 flower so high that it stood above the level of my eyes, in 

 order to be able to look into it from below, the pollen fell 

 in large amount out of the funnel, like writing sand from 

 the sand-box, as soon as I lifted the style with a slender 

 stick. This phenomenon, which actually startled me, 

 because I had not expected it, was to my understanding 

 what a -flash of lightning on a dark night is to the eyes, 

 it revealed on a sudden the whole secret to me." 



Oenothera speciosa (or other species). 



What is the habitat of this plant ? Describe the leaves. 

 What sort of an inflorescence has it ? Observe the arrange- 

 ment of the floral parts in the bud. At what time of day 

 do the flowers open ? How long does a flower last ? 

 Describe the calyx of an open flower. Do the anthers 

 dehisce before or after the flower opens ? Are the stigmas 

 ready to receive the pollen as soon as the flower opens ? 

 Draw the upper part of the style before and after the 

 branches spread apart. Note the position of the style 

 branches when the flower first opens. What are the 

 relative positions of anthers and stigmas ? Could self 

 pollination take place if cross pollination does not ? What 

 significance do you attach to the cobwebby pollen ? Do 

 the flowers become more fragrant in the evening ? Where 

 is the nectar secreted ? How long must an insect's pro- 

 boscis be to get it ? At what time of day do insects visit 

 these flowers ? With their present habits, would it be as 

 well for these flowers to be any other color than white ? 

 Make a longitudinal diagram of a flower and a cross dia- 

 gram of an ovary. Compare with the types of flowers of 

 Fig. 123. To what type does this flower belong? What 



